Laminated sheet



March 3, 1942 P. ZALKIND LAMINATED- SHEET Filed May 14, 1935 aSheets-Sheet 1 ATTORNEY March 3, 1942, P.ZALKIND 2,274,765

LAMINATED SHEET I Filed May 14, 1935 s Shets- Shee t 2 PHILIP ZALKINDINVENTOR BY I $4 @117" ATTORNEY -Ma.rch 3, 1942.

P, ZALKIND 2,274,765

LAMINATED SHEET Filed May 14,1935 3 Shets-Sheet aIII/I/I//I//I/I/////I/Ill/I/I//// flu-Z3237 .1

FIG. 28

Q PHILIP ZALKIND INVENTOR 9% New 1w ATTORNEY IQ C 6 Patented Mar. 3,1942 UNITED STATES PATENT OFFICE LAMINATED SHEET Philip Zalkind, NewYork, N. Y. Application May 14, 1935, Serial No. 21,4].1

' the stored line determined by the fibrous materlal. l

6 Claims.

. comprising a lamina of metal and a non-metallic lamina the fold lineof the combination being produced by conditioning the non-metalliclamina.

I have discovered that scored fibrous sheet material may be combined inlamiform union with sheet metal such as steel or the like by suitableadhesive such as silicate of soda or various adhesive compositions suchas are readily procurable on the market and that such a lamiform orsectional combining of sheet material with scored fiber sheet willpermit bending of the combination along a predetermined line without anytreatment of the metal for predetermining the bendin line or lines,provided the fibrous material is of dominating rigidity in relation tothe thickness and torsional resistance of the metal. The scoring of thesheet board material may be accom plished either before the unionthereof with the metal or after union. In scoring after lamination ofthe board and metal, I have found that the metal remains unaffected.

I am aware that the combining of metal foil with paper materials is acommon practice but I contemplate the use of metal of such gauge andstrength, as distinguished from foil, that it adds definitely to thestructural strength of the combined sheet. The metal I use hassubstantial body and could support itself in a horizontal position for asubstantial length. It has considerable compressive and tensile strengthand could not be manually torn apart. In itself, however, it bucklesreadily when subjected to compression. I

have found that combining this metal with scored corrugated board orsuch other sheet material as herein referred to, produces an article ofmanufacture which can carry a substantial vertical compressive lcad, themetal supplying the strength and the board supplying the body. I havefound by numerous experiments that metal of the thickness of 30 gaugeand heavier may be so combined and dominated as to predetermined bendinglines when combined with other sheet material such as corrugated board,wall board, plywood, and the like without the requirement of providing ascoring or weakening in the metal to assist the predetermining of thebending lines in the metal.

In order to provide coordination of the juxtaposed edges and preventexcessive strains at the bending line where wood is used, I may spacethe wood sections from each other so ithat they are juxtaposed when thematerial is bent along I have found that this lamiform construction withrelatively light metal will have the benefit of the bulk provided by theaddition of fibrous material. Moreover, it will have the added rigidityattained from such combination and will not have the tinnysound or.efiect incident to the use of sheet metal alone even where the metal initself is of sufiicient thickness or bulk to provide the requiredstrength.

It is obvious that this composition comprises a new article ofmanufacture adaptable for many uses in addition to specificillustrations thereof.

It is further my intention to provide in structures such as those hereindescribed the quality of fire resistive protection. In combining; asabove described, sheet metal and paper by means of silicate of soda, avery definite measure of fire protection is acquired by th structure,the silicate of soda itself lending fire resistive quality by itsapplication to the paper material,- and whereasordinarily theapplication of silicate of soda on paper causes it to be brittle and tolose strength, its use in this manner .does not weaken or lessen theeffectiveness of the fibrous material in the structure for its intendeduse here.

In fact, I have discovered that I can impregnate corrugated board'of lowtest or of non-test in a bath of fire resistive adhesive, as forinstance, silicate of soda solution, and apply the lncombustible sheetmaterial such asasbestos corrugated board thus treated to a sheet ofmetal, such as steel, using the silicate of soda as a'cementingmaterial. The laminated sheet thus formed possesses considerablestrength, and the corrugated board thus treated lendsa greater strengthto the combination than does untreated corrugated board of the sametest. Similar re-- sults may be obtained in the same manner with varioustypes of sheet material.

I mayalso make such a combination with an board, which in the formsordinarily used commercially has insufiicient strength by itself .for

' any such constructions as are herein disclosed,

but which by combination with the metal as herein disclosed, serves togive body and rigidity to metal and the thin metal in the combinationserves to give' the necessary strength for the structure.

Furthermore, the combination of fibrous material and metal may haveinterposed between them sheet material, such as asbestos paper to add tothe fire resistive qualities of the container. Also I may treat bothsides of the fibrous lapsible containers.

' It may be used for wall structures and by suitmetallic layer or incombination with a plurality ably providing fold lines at properintervals may be bent around angles. It is thus readily adapted to beused in providing a metal faced, fire resistant sheathing on columns, orit may be used for flexible panels or partition screens. Also myinvention is especially adapted for use in col- It may be readily usedto provide an inexpensive metal lined shipping container that may becollapsed till ready for use; or it may be used with metal facedfurniture of various shapes and uses, such as filing containers anddrawers, as well as other furniture, such as cabinets. In my copendingapplication, Serial No. 739,962, filed August 15, 1934, I have disclosedth'e use of my lamiform combination sheet in connection with cabinets.The present application is a continuation in part of the aboveapplication, Serial No. 739,962. However, I do not limit the use of mylamiform sheet to use with cabinets; neither do I limit its use to thespecific purposes recited in this paragraph, as its uses are many andvarious and the particular form is susceptible of considerable variationwithout departing from the scope and meaning of my invention.

Thus, depending upon the use to which my invention is to be adapted, Imake use of various combinations of materials in layers, one of which ismetallic and another of which is non-metallic and which by its conditiondetermines the fold line on which the combination will bend.

In general for the non-metallic layer I can use either cellular materialor solid material. The cellular material may be corrugated board,corrugated asbestos sheet, or the like; and where such corrugatedmaterial is used it may have a liner on both sides, or on only one side,or the metal may itself be the liner on each side.

Where solid material is used in the nonmetallic layer, I can use eitherbending or folding material, such as fibre board and pap board; ornon-bending or non-folding material, such as veneer, wood ply board,asbestos board, wall board, mineral composition board and chip board.

The metallic layer I prefer in general to be sheet metal of the order of30 gauge thickness, but other thicknesses may be used depending upon.the strength and thickness of the nonmetallic layer in which thepredetermined bending line is incorporated and the specific applicationor embodiment of the invention. Thus I have used steel over 26 gaugethickness and thinner than 38 gauge. Other metal than steel may be used;but I prefer the use of steel mainly because of its relatively low costand high tensile strength. However, I am not limited to steel for themetallic element, as zinc, copper, tin.

aluminum, brass, or other metals may be used. I can use the laminatedsheet in various combinations as to the position of the metallic memberin the laminated structure. Thus I can use a single metallic layer inthe combination, and

such single metallic layer may be on'one of the two surfaces of thesheet, or it may be'used in combination with a plurality of Inon-metallic layers and may be covered on either or both sides by such alayer. Also, I can use a plurality of metallic layers in combinationwith a single mmof non-metallic layers. Where two metallic layers areused, each layer may form one of the.

outside layers of the sheet, thus presenting an entirely metal-cladsheet.

The laminated sheet may be made fireresistant, either by using anaturally fire resisting material, such as corrugated asbestos or otherasbestos sheet as-the non-metallic element; or by impregnatingthe-'non-metallic element to make it fire resistant. I have alreadyexplained how the use of silicate of soda as an' adhesive material addsto the fire resistive quality of the non-metallic layer. Another meansfor providing fire resistive quality is to impregnate the non-metalliclayer with a chemical which will evolve an inert gas when heated. Thisis par-- ticularly effective when the laminated sheet is metal cladentirely over bothsurfaces, as the impervious character of themetalcovering will prevent either loss of chemical through volatilization orloss of gas when the chemical is decomposed by heat.

Various means may be used in joining the various layers of my laminarstructure, and the means best suited will depend upon the Specificapplication. Thus, I may use an adhesive mateespecially effective when ametallic layer is placed on either side of the non-metallic layer,the'metal on one side having the punchedprongs which extend through thenon-metallic layer into corresponding piercings in the metallic layer onthe other side. It is obvious that both the above methods of fasteningmay be combined in the same structure, or that riveting means may heused instead of prongs as a mechanical fastening means. Also where' onlyone sheet of metal is used, I may use metallic washers or clips on theside away from the metal for backing the non-metallic element to receiveand cooperate with the prongs, rivets or similar fastening means.

Where adhesive material is used to join the various layers, I may applythe adhesive material directly between the layers or may interpose alayer of paper between the layers to aid in binding the layers. Thus injoining a metallic layer to a non-metallic layer, a soft paper capableof readily retaining adhesive substance may be first applied to themetallic layer; and the metallic layer, with the paper backing, appliedto the non-metallic layer through the medium of the adhered paper. Inthis manner it may be possible to obtain a more complete and uniform anda more secure joint between the metallic layer and the non-metalliclayer than if the metallic layer' were adheslvely connected directly tothe non-metallic lamination. In such a modification it becomes practicalto use adhesive or plastic material of varying characteristics betweenthe laminations.

The objects of my invention are to provide the advantages of a metalsurface with the lightness, cheapness, bulk, body and rigidity of anon-metallic sheet; to eliminate the tinny sound of thin sheet metalstructure by combintially impervious. sheet suitable for collapsible lcontainers, cabinets, boxes, and the like.

It will be seen from. these specifications thatthe above and otherobjects are accomplished by my invention.

My invention may be further explained in i conjunction with theaccompanying drawings which show a number of the various modificationsby way of illustration but which are not intended to exhaust the variousstructural changes which may be made within the scope 20 of myinvention. In the. drawings, which form a part of this specification:Fig. 1 is a plan view, partly broken away, showing a sheet constructedaccording to my invention;

Fig. 2 is a cross-section along the line 2-2 of Fig. l;

Fig. 3 is a longitudinal section through a prong on the line 3-3 of Fig.1;

Fig. 4 is a cross-section similar to Fig. 2 show- 30.

ing the sheet bent at the score line;

Fig. 5 shows in cross-section an alternative form ofsecuring thelaminations;

Fig. 6 is a plan, partly broken away, of a modifled sheet constructedaccording to my invention; 35

Fig. 7 is *a cross-section along line I--'|- of Fi 5; Fig. 8 is a crosssection similar to Fig. 6 show-' ing the sheet bent at the score line;

Fig. 9 issimilar to Fig. '8, with the sheet ben in the oppositedirection;

Fig. 10 is a modified cross-section; FlFigbll is similar to Fig. 8,using the score 0 Fig. 12"is similar to Fig. 9, using the score of 4Fig. 10; ti Fig. 13 is a plan view .01 a. further modificaon; 1

Fig. 14 is a cross-section on line ,ll-H of Fig. 13; 50

. Fig. 15-is -a cross-section similar to Fig. 14'

with the sheet bent at the score line; Fig. 16 is a cross-section of afurther modification of my invention along linel6 l6.oi Fig. 17;

Fig. 17 is a plan viewof Fig. 16; 55

Fig. 18 is a cross-section showing means 0 confining the bend line to asingle one of two lines and is along line la-ia of Fig. 19;

Fig. 19 is a plan view of Fig. 18;

Fig. 20 is a longitudinal section along line 20-40 of Fig. 1a;

Fig. 21 is a plan view of a further modification;

Fig. 22,is-a cross-section along line 22-42 of l Fig. 21; I Fig. 23 is alongitudinal section along line' 23-1-23 of Fig. 21; a

Fig. 24 is.an enlarged section;

.Fig. 25 is a stress diagram showing the laminar:

sheetas a section of a beam; i 70 Fig. 26 is a plan view showing a threeply laminated sheet with an alternative fastening v means;

'Fig. 27 is a cross-section along line 21-21 of Fig. 26; T

2,274,765 I 3 Fig. 28 shows one application of my laminated.

structure: Fig. 29 shows another application of my invention;

Fig. so is a view of m. 29 in the collapsed l.

position; i

.Fig. 31 shows a modified form of the joint illustrated in Figs. 29 andFig. 32 is a. -further modificationof Fig.3l;

Fig. 33 is a plan view of a further modification similar to Fig. 13. Y

Referring to Figs. 1, 2, and 3, Ihave shown a multiple ply structurewith the center lamination I of corrugated board. This corrugated boardis, shown as comprising the liners 4 and 4' and the corrugations 5. Oneither side of the corrugated board is shown a layer of insulatingmaterial! and 2' which may be asbestos paper or the like. The two outermetallic lay, ers 3 and 3 are preferably of sheet steel of thickness offrom 26 gauge to 38 gauge.

The dominating layer l of corrugated board is provided with a score line6, which I have shown as a crease-line. I have found that this scoreline will control the entire laminate structure, so that when the sheetis manually bent it will bend on this score line substantially as shownin Fig. 4. The score 6 is preferably formed,

in the non-metallic layer prior to its combi nation with the otherlayers asa unified structure: and with some of the material which I usein thenon-metallic layer'itis necessary that the fold line beincorporated with the sheet either prior to or during its assembly.However, when I use easily scorable material, such as corrugated boardfor the dominating lamination, the scoring may be done after the sheetis completely assembled, if I use suitable scoring means,

and the score 6 provided in the lamina|, through the laminae .2 and 3without marring' or otherwise aiIecting the metallic layer 3.

As shown in Figs. 1, 2 and3, the severallayers of the sheet are'held inrelation to each. other by means of the prongs I punched out of themetallic sheet 3. In addition to these prongs which pass throughthe-several layers of mate-- rial, adhesive may be used to.cons'olldatethe layers and to prevent one layer from sliding on anadjacent layer. The prongs 1, preferably an of sufilcientlength that,they coact with the small slots 3 punched in the metallic sheet 3-,

These prongs I are "shown as having been' punched out with the'tit. It.The distance from the start of the tit to the inner face of metalliclayer 3 is substantially equal to the thickness of the non-metalliclayers. Thus the tit' enters the slot 8 in sheet 3' and the shoulderformed-where the tit it joins. the main prong 1 acts to keep the twometallic sheets in spaced relationship to each other a distance equal tothe thickness of the non-metallic member. The ends I330! the prongs I,may be held within the-slot 8 by any suitable means and thus, securelybind the whole structure together.. The shoulder; on the prongs, whichspace the metallic members apart,

are particularly desirable when the ends [6 are rolled or riveted intothe slots 8.

In the upper portion of Figs. land 3, I have shown an alternative forrnof prong I. As shown in Fig. l, the prong is are shaped in section. Thisaddsmaterially to the strength of the prong; and it sheet 3 from whichthe prong i is formed is of. heavier gauge than sheet 3', the prong maybe made to pierce and. penetrate l sheet 3', thus forming theelot 8 withwhich the pr g cooperates. In the operation by which the prong is driventhrough the sheet 3', the end of the .prong may be turned over as shownat I! (Fig. 3), thus clinching the laminations securely together.

An alternative method of forming the prongs is shown in Fig. 5. In, thisfigure prongs are formed from both the metallic layer 3 and the metalliclayer 3', the prongs being formed alternately from the two sheets. Theends of the prongs I from the upper metallic sheet 3 pass through thenon-metallic layer I and instead of passing through the metallic layer3' are turned over and clinched into the non-metallic layer as at II..The prongs 1" formed from the lower layer 3' also pass through thenon-metallic layer and areclinched into it as at H". The clinching fromboth sides through one of the interior layers firmly unites all ofthe'layers into an integrated structure.-

- It is of course understood that there may be used a greater orlessernumber of layers than five as shown in Figs. 1 to 4. In Figs. 6 and 7,

I have shown a two layer sheet in which the two layers are joinedtogether by adhesive material alone. In these figures, I is thenon-metallic layer and 3 is the metallic layer, and the score 6, in thenon-metallic layer is shown as a cut score. type of score is preferablewhen such material as veneer, wood plyboard, asbestos board, wall board,mineral composition board, and similar material, which cannot be easilycreased is used as the non-metallic layer,- but a cut score may also beused with an easily creasable non-metallic layer such as paper board orcorrugated board. When material such as chip board, paper board, ormaterial of cellular structure is used'as the non-metallic layer, thebending'may be away from the metal as shown in Fig. 8 without exertingany considerable pressure. As a certain amount of crushing. of thenon-metallic layer takes place when the sheet is bent in this way.relatively dense and un yielding material, such as wood ply board wouldrequire considerable stress applied to make this form of bend, but itwould bend on the predetermined score line.

In Fig. 9 I have shown the sheet material of Fig. 6 bent toward themetal layer. In this case there will be an unfilled corner 9, but littlestress is required to make this bend even if the material of thenon-metallic layer is quite dense and 'unyielding.

The necessity of high stress application during bending and the opencomer may be obviated by slightly modifying the score line. Thus, asshown in Fig. 10, thescore 6 is shown as a cut-out rectangular V notchin the non-metallic layer'I of ,3-ply wood adhesively attached to themetallic layer 3. When .this structure is bent away from the metalliclayer along the score line 6 as shown in Fig. 11, the sides of the Vnotch approach each other and form a miter Joint'when the sheet is bentto a right angle. When'the sheet with this form of score line is benttoward the metallic layer, as shown in Fig. 12, the score 6 will open upand when the sheet has been bent to a right angle, the score line willbe presented as a bevel .edge I0. As is ob; vious, variations in theform of cut-out scores can be made to produce a great variety of cor nershapes and angles.

A further modification of the cut score is shown in Figs. 13, 14 and 15.The same effect as by scoring a sheet of non-metallic material hasseveral particular advantages.

is obtained when two separate pieces of material are laid edge toedgeand combined with the sheet I being somewhat thicker than sheet I,

as clearly shown in Fig. 14. In laying up the structure, the edge ofsheet I may be suitably spaced from the edge of I. Where solid-material,such as ply wood, etc., is used, this distance should be slightly lessthan the thickness of the thinner of the two sheets; but where yieldablematerial like corrugated board provides one of the edges, spacing maybe' unnecessary. When the sheet is manually bent along the score lineIi, the thicker of the two sheets will ride on the thinner sheet andform a tight fitting corner without strain or distortion of thenon-metallic layer as clearly shown in Fig. 15.

Where, the material of the non-metallic'layer is easily yieldable, suchas corrugated board, the sheets I and I'- may be of the same thicknessas each other, but the same effect as that obtained from sheets of twothicknesses may be secured by slightly crushing one of the sheetsadjacent to the score line and for a width equal to or slightly greaterthan the thickness of the un crushed sheet. By this means, the crushedportion will act in the manner of the thinner of the two sheets shown inFig. 14 and the thicker layer will ride on top of it in bending up anangle in the manner as shown in Fig. 15.

In the modification illustrated in Fig. 15,.I have shown prongs punchedout of the metallic layer functioning to unite the, laminations. (Thesemay be assisted by adhesive material between the layers.) through thenon-metallic layer and are clinched over the straps II made of metal orother suitable material. It will be .noted that as shown incross-section in the upper part of Fig. 13, the prongs are shaped topresent a convex surface on the side adjacent to the strap I I. Thisshape First, the prong has greater strength than would a flat prong ofthe same thickness of metal, and it is therefore forced more easilythrough the nonmetallic layer. Second, the prong is pressed through thenon-metallic layer against an unyielding backing, the arcuate shape willcause the end of the prong to bend toward the convex face when itstrikes the unyielding surface, using the principle which I havedisclosed in my copending application, Serial No. 693,841, filed October16, 1933. The prong will thereby be bent so as to clinch over thebalcking strap II.

When the two members I and II of the nonmetallic element are spacedapart, there may be need for further means -to precisely determine thebend line as to the particular edge of said space, otherwise the bendmight come .indiscriminately at the line to, orline 6b, orintermediately. The "difference in thickness of the materialpredetermines the bend line at the line 6b as shown in Figs. 13, 14, and15 However, this same efiect may be obtained in other means,- using anon-metal layer of uniform thickness.

, In Figs. 16 and 1'7 I have shown in cross-section a modification of 'ascore line obtained by laying the non-metallic sheets I and I with theiredges adjacent to each other but so spaced from each other as to providea crease line of appreciable width. In this figure, sheet I and sheet IThese prongs I pass are shown to be the same thickness, but though thescore 6- is of appreciable width, the bend line is restricted to a linealong Go by the insertion of the strip I2 whichgprovides a greater bendresistance to the combined sheet at the line along to than is presentedby the sheet at the line along 6a. This definitely predetermines thebend to the line at Go. Strip I2 may be or any suitable materialproviding bending strength exceeding the variations in strength of themetallic layer 3.

Where the score line is of such width as to provide more than one lineon which the sheet could bend indiscriminately, the limitation of thebend line to a single predetermined line by providing differentialstrength of the several possible lines of bend may be accomplished inother ways than that shown in Figs. 16 and 17. A slight increase inthestrength of the metallic sheet across one of the two possible bend lineswill confine the bend to the other line. Such a modification is shown inFigs. 18, 19, and 20. Here the metallic sheet 3 is provided withcorrugation or rib formations I3 extending over the edge to ofnon-metallic-sheet I; but this corrugated or rib formation I3 does notextend over the edge -6a of non-metallic sheet I. The strength of thelaminated unit is thus greater at edge 61) than it is at edge 6a, thus apredetermined bend line occurs along the line at to.

I have found that where the non-metallic layer is wood ply board or.similar material, an

- effective predetermination of the bend line may be secured using lockjoint construction as shown in Fig. 33. In this figure, the metallamination is shown at 3,-and the bend line occurs along the space at '6between the separate non-metallic sheets I and I. The non-metallicsheets I and I and the metallic sheet.3 are secured together by-anysuitable means, as for instance, by a proper adhesive substance.

Each of these spaces 3| is defined by the corners I p a, b, c and d.

- tallic member, may have the portion to the left of the bend linepreciselyspaced for a perfect lock joint-by properly proportioning theholes 3| 15 and 3|. When the laminated sheet thus formed is bent alongthe bend line, the jointures cb.

The joint thus formed will and do will shear. be exactly the same as ifthe portion of nonmetallic member left .of the bend line had been aseparate piece from the portion to the right of the bend line, and atthe same time the two pieces had been perfectly spaced from each other.

A further modification of my invention is shown in Figs. 21, 2, and 23.In this modification the metallic layers 3 and 3 act as liners for thenon-metallic corrugated layer I. this form the laminar sheet quite stiffand must be shipped fiat; but if the metallic member 3' is omitted andthe sheet consists only of a single metal liner 3 with the corrugatednonmetallic backing I secured thereto, then the sheet may be shipped inrolls.

It has heretofore been pointed out in this specification that thelaminated sheet has considerably greater strength. thanhas either themetal The member I is provided with the line ofj projections 29 andtheline of grooves 30. The member I' is provided with the line ofprojections 29' and the line of grooves 30'. The projections-290i sheetI fit into the grooves 30 of sheet I; and the projections 29 of sheet I'fit into-the grooves 30 of sheet I; If the distance betweeen the extremeends of the projections 29 to the bottom of the grooves 30' and from theendsof the projections 29 to the bottom of the grooves 30 issubstantially equal to the thickness lic layer or the non-metalliclayer. In Fig. 24 there is shown an enlarged section of a laminatedsheet consisting of the dominating nonmetallic member I and the metalliccovers 3 and 3'. The dominating non-metallic member is indicated asbeing a sheet of corrugated board with the liners 4 and 4' and thecorrugated paper web 5. I V

If it is assumed that the metallic members are made up of sheet steel of#32 gauge (.01")

- thick, and that the corrugated board is /8" thick of sheets I and I,then the laminated sheet may be manually bent along the bend line 6 toform a perfect lock joint between the non-metallic members I and I' tohave a sharp linear bend in the metal.

It will he noted that if the sheets I and I are spaced eithertooclose'together-or too far apart and if a thin metallic layer is used,then when the laminated sheet is bent in to right angular form toproducea lock joint in the nonmetallic members, the outline of the teethof the lock-joint may be perceptible in the metallic member 3. This canbe entirely obviated by careful spacing of'the sheets I and I, which mayor by the means which I shall now describe.

It will be noted thata line of rectangular cut out spaces 3| is formedwhen the projections 29' are fitted into the grooves 30. Each of these'be accomplished through the use'of proper jigs;

spaces 3I is defined by the corners a, b,'c, and d.

Similarly, a line of rectangular cut out spaces with 12;" liners, thenthe total laminated sheet is approximatelyllz'f' thick. The safe bendingmoment of each of the steel sheets taken alone is representedby so thatthe two sheets taken separately will have.

' laminae are properly secured to each otherin such a manner that theadhesive strength is greater than the horizontal shearing forces thatare developed by beam loading, the structure will withstand a muchgreater moment. This is represented diagrammatically in Fig. 25 whereinI4 and I4 represents the safe stress in the steel coverings and I5 andI5 represents the stress in v the cardboard liners.

Under these conditions the combined safe bending moment will beapproximately 70b inch pounds, which is many times the bending strengthof any-of the separate laminations. ,In this-respect, the structureresembles aslab of reinforced concrete, where the steel v alone hassubstantially no bending strength, and 3 I is formed by projections 29and grooves 30. 7 the concrete alone has but little more: but when- Thissingle sheet, in which the posite metallic layer.

the two are properly combined, there is produced a structure of greatstrength due to the proper spacing of the high strength material so asto develop a moment. a

Likewise my metal clad structure is capable of acting as a vertical wallto support a vertical load in columnar relationship. As a verticalcolumn, the metal as defined at No. 32 gauge would have a radius ofgyration of-about .003", and with this radius could not support avertical load as a column for a length greatly in excess of /2" inheight. When properly combined with the corrugated paper so that thelayers are secured to each other in a manner to develop web stresses,then the radius of gyration, for the same dimension sheet as was usedabove in figuring beam stresses, becomes about 1%" and is thereforecapable of supporting some load for a column height up to over a foot.By slightly increasing the thickness of the corrugated board the sheetmay be designed to carry loads of greater height as desired, but thedimensions as given above are quite suitable for structures such ascollapsible filing cases of the usual dimensions.

In Figs. 26 and 27, I "have shown a laminated sheet formed from themetallic layers 3 and 3' and the non-metallic sheet I. In thismodification. prongs l are formed in both of the metallic layersand'coop'erate with the slots 8 in the op- The ends l8 of the prongspass through the slots 8 and are clinched over at When, as shown in Fig.26, the prongs not only are formed in each sheet but also arealternately placed in ,each sheet so as to face in a differentdirection, a laminated sheet of great strength is thereby produced. Thetapering portion of the prongs alternately coming from either metallicsheet and alternately facing in difierent directions on each sheet addsgreat stability-to the entire structure and develops web stresses sothat the sheet is quite strong either as a beam.

Figures 28, 29, and 30 serve to illustrate several of the possible usesfor my invention. In Fig. 28 there is shown a section of a collapsibletube adapted for use where a metallic surface, hermetically sealedcontainer is required. In

this figure the non-metallic layer is represented at I with the foldlines illustrated along the lines 6. It will be noted that, as shown,the metallic layer and the non-metallic layer are not coextensive inthis illustration. The non-metallic layer' is provided with the fiap ontab l9 provided with the adhesive strip 20. When the laminated sheet isbent up as in Fig. 2!}, the ad hesive strip 20 serves to unite the twoends of the ment is provided with the flap or tab l8. This tab may betinned on the inner surface as at 2|. When this tab is turned down theinner tinned surface 2| coacts with the outer tinned surface 2| on theangular tube. By properly applying heat along the 'outside of tab l8, aclose juncture will be obtained by uniting the solder of the twoabutting tinned surfaces, thus forming an impervious metallic layerentirely surrounding the non-metallic layer. The tube so formed will becollapsible until heads are applied 'non-metallic' element. Also themetallic eleto the end of the tubes. These, heads maybe I formedeither'from flaps provided on the main sheet or they may be separatesheets as shown in' my copending application, Serial No. 693,841, filedOctober 16, 1933. In either case, abutting tinned seams similar to thatproinded on tab I! may be provided on the joints of the head connection,whereby the box thus formed will be hermetically tight after all thejoints are made In Figs. 29 and 30, there are shown illustrations of theopen spaced crease line as explained in Figs. 13 to 19 inclusive. InFig. 30 is shown the tubular structure of Fig. 29 in collapsedcondition. It will be noted that on the bottom of Fig. 30 is shown ajoint of the same type as shown in Figs. 16 and 17 with the strip l2provided to cause the bend to occur along the line 6a. No

such strip I2 is shown at the jointshown on the upper part, of Fig. 30,but the effect of such a strip is obtained by properly lapping the twoends of the metallic sheet when they are brought around to contact eachother and to be united with each other by any, suitable means, such assoldering. In this case, the portion 23 overlapping the portion 22serves the same purpose as does the strip l2 acting with the sheet 3 onthe joint on the lower portion. Thus the bend line will occur at 6arather than at 61).

'Many variations of this means of conditioning the bend line may be usedin my invention, andtwo such modifications are shown in Figs. 31 and 32.In these figures are shown means for-joining the two edges of a' singlesheet to form a collapsible tube, such as is shown in Figs. 29 and 30,either Figure 31 M32 showing a modification of the joint shown as theoverlapping edges 22 and 23 in the-upper portion of Fig. 30 and in theupper right hand corner of Fig. 29.

While I have shown the joined elges in Figs.- 29 and 30-as being thetwoopposing edges of a single sheet, ,it is clearly indicated in Figs.31 and 32 that the joined edges may be either the opposing edges of asingle sheet formed into a tube, or they may be abutting edges of twoseparate sheets. Thus as in the case of a tubular structure such asshown in Fig. 29, each of the four sides may be covered with an integralmetal sheet; or if desired, each of the sides may be an individual sheetof metal joined to the adjacent metal sheets by a joint such as shown inFigs. 31 and 32.- In this way there will be formed an integrated builtup sheet with the -bend lines predetermined in the sheet in accordancewith my invention.

Referring to Fig. 31, the dominating nonmetallic material is shown at laand lb and may be either a single sheet with a cut out score 6 .or maybe two separate sheets laid adjacent to each other to form the score 6.The metallic layer is shown as at 3 and 3' and may be either a singlesheet forming opposed edges of a sheet bent to tubular form or may betwo separate sheets, as has just been explained. The edge of sheet 3 isbent ,into a U at 24 and the edge of 3 is bent into a U at 25. These twoU-shaped edge bends are united to each other by the strip 26, which fitsover the outstand leg of each of the U-shaped edges, and is preferablypressed or rolled after being placed in such position. In

to each other. The bend line is conditioned in the laminated sheet thusformed at the score line 6. Moreover, the union of the metallic layerwith the multiple ply of metal overlying the edge 6b, but not overlyingthe edge 6a, predetermines the line of bend exactly at 6a.

Fig. 32 is similar in every way to Fig. 31, except that another form ofseam for joining the sheets 3 and 3 is shown. Thus instead of the metalstrip 26 being used as a tie piece for joining 3 and 3', the sheets 3and 3' are bent over and crimped on each other to form the joint.However, as in Fig. 31, the seam by lying over the edge 6b,predetermines the bend of the laminated sheet at 6a.

It will be understood that these examples are given merely to indicatein what manner my invention can be used, and that my inventionis not atall limited to these specific examples, but

instead has a broad general application for' numerous purposes.

Many changes maybe made in the my invention without departingfrom thescope thereof. Having described my invention in such a manner that itmay be readily understood by one skilled in the art:

I claim:

1. As an article of manufacture for forming collapsible containers, acomposite sheet of laminar material comprising a thickness of papercomposition material of dominating rigidity securely joined to twolayers of. sheet metal of the order of 30 gauge, one on each side ofsaid paper composition material, and a crease score line in said papercomposition material formed without loss of paper fromsaid papercomposition material for determining a bending line, in said article ofmanufacture.

2. As an article of manufacture for formingcollapsible containers, asheet of paper composition material; a sheet metal facing on each faceof said material; and means for securely joining the several layerstogether, said joining means including prongs formed by punching outportions of one of said sheet metal facings, said paper compositionmaterial having a score line formed without loss of paper from saidpaper details of composition material for'determining the bend line ofsaid article of manufacture.

3. As an article of manufacture, a sheet of laminar material comprisinga thickness of nonmetaliic material securely joined to a layer of bendline, said bend line being determined by the said non-metallic materialbeing discontinuous along said bend line and by a stifiening strip theedge of which is laid contiguous to said bend line, said strip beinginterposed between said metallic and non-metallic layers.

5. As an article of manufacture, a sheet of laminar material comprisinga thickness of nonmetallic material securely joined to a layer of Isheet metal, said sheet having a predetermined bending line, said bendline being determined by the said non-metallic material beingdiscontinuous along said bend line and by corrugations formed in saidmetallic layer transverse to said bend line and terminating at said bendline.

6. As an article of manufacture, a sheet of laminar material comprisinga thickness of nonmetallic material securely joined to a layer of sheetmetal, said sheet having a predetermined bending line, said bend linebeing determined by the said non-metallic material being discontinuousalong said bend line and by a multiple ply of metal formed from themetallic layer along said bend line, an edge of said multiple ply lyingalong said bend line.

PHILIP ZALKIND.

